Electrical Taping Skills: A Lost Art?

1 With all of the new products and Electrical insulation kits cur-rently on the market, the use of conventional Electrical tapes has gone down. As a result, electricians today may not possess the Taping skills that once were such an important part of their predecessors work. Nevertheless, there is still good reason to master this craft especially for those times when repairs are needed quickly and other products are simply not to Steve Anderson, a National Joint Apprenticeship and Training Com-mittee (NJATC) director, the NJATC believes strongly in the importance of splice and termination Taping skills for electricians and linemen. Taping is the fi rst thing covered in our cable splice training course, and we spend a lot of time in this area, Anderson says. Electrical Taping Skills: A Lost Art?Although some may consider the practice old school, Electrical Taping is a valuable skill you shouldn t let slip awayBy Bob Goodman and Rodney G.

2 Brown, 3 MThree different types of tape are used to connect feeder cables to motor leads. In the last step, a quality vinyl Electrical tape is stretched as it is wrapped for good conformance to the underlying structure and to complete the moisture seal. This tape withstands the effects of vibration while providing Electrical insulation and protective tape application enhances adhesion and insulation points out that repair situ-ations can arise in the fi eld where a splicer does not have access to a particular kit for the job. However, knowing how to make proper use of tape can save the day, getting the customer back online quickly. It s far more economical to complete a job on the spot with tape than to go in search of a kit, Anderson tips. The primary tapes used in Electrical applications are vinyl , rubber, mastic, and varnished cambric.

3 These products have been used in Electrical work for many years, are code approved, and conform to key industry standards, including UL 520, ASTM D1000, and CSA The Table on page C23 lists the primary uses for each of these types of function of moisture-sealing tapes such as vinyl , rubber, and mastic products is to exclude moisture from the insulation assembly and provide electri-cal insulation. One of these tapes or alternately a mastic pad generally forms the second layer of the insulation assembly. Rubber, mastic, and filler tapes are also used to pad the underlying surface by covering sharp tapes are generally non-adhe-sive, and are either equipped with a liner or are linerless. Stretched and overlapped l ayers w i l l f u s e or bond toge t her to for m an effective Electrical insulation and moisture barrier.

4 For low-voltage (1000V or less) applications, rubber tapes should be stretched during wrapping so that tape width is reduced to approximately 75%. For high- and medium-voltage ap-plications where the Electrical stresses are high ( connector areas, lug areas, and cable shield cut-back areas) tape should be stretched just short of its breaking tape forms the fi nal outer layer and serves several important functions in addition to Electrical insulation, including abrasion protection, cor-rosion resistance, UV resistance, and protection from chemicals including alkalis and acids. Conformable vinyl tape is tougher than the softer, stickier surfaces of rubber, mastic, and putty tapes it grades of vinyl Electrical tape are available all of which differ in conformability, ease of unwinding, resistance of the adhesive to heat and cold, and loosening (fl agging).

5 While general-use vinyl tapes are appropriate for bundling, wire pulling, and other ancillary tasks, premium-grade vinyl tape is the best choice for permanent insu lat ion work as it ha nd les t he broad-est range of environmental factors and functions, such as cold should use a minimum of two half-lapped layers of vinyl tape to insu-late and jacket low-voltage components. A half-lap (see Figure above) consists of overlaying each turn by one-half the width of the tape . The general rule of thumb calls for a tape thickness of times the thickness of existing wire or cable insulation. In every case, tension on the tape should be suffi cient to con-form the tape evenly to the surface. A slight reduction in tension is encouraged for the fi nal wrap. Trim the tape end and allow it to return to shape before pressing down with the thumb to avoid lifting or fl applications.

6 When properly applied, quality tapes can serve as valu-able standby resources for jobs such as insulating motor lead connections, inline splices, and split bolt and bus bar connections. Let s take a look at some guidelines for lead insulation. In the case of low-voltage motor lead connections, the tape insulating process consists of con-necting feeder cables to motor leads and arranging the conductors for easy wrap-ping. You should begin by wrapping two layers of varnished cambric tape , which is available with or without adhesive. For the adhesive type, apply with the adhesive side out for clean up this fi rst step by wrapping fou r ha l f-lapped layers of r ubber i nsu lat-ing tape over the cambric tape , which creates a moisture barrier and provides the primary insulation in the connection. Finally, over-wrap the assembly with a minimum of two half-lapped layers of vi-nyl Electrical tape .

7 This should extend ap-proximately two tape widths beyond the ends of the rubber tape . Stretch this tape as you wrap it so you get good confor-mance to the underlying structure. This also helps complete the moisture splice insulation. You can pro-tect a low-voltage inline splice in a similar manner by wrapping the installed con-nector with four half-lapped layers of rubber mastic tape or rubber splicing tape , and then over-wrapping it with two half-lapped layers of premium vinyl Electrical bolt connection. Protection of a split bolt connection begins with install-ing the connector and wrapping it with two layers of varnished cambric tape . Next, wrap the splice with four half-lapped layers of rubber or rubber mastic tape . Complete the job by over-wrapping with at least two half-lapped layers of Tale of the TapeThe fi rst commercial tape for Electrical insulation was cotton friction tape , which became available in the early 1930s.

8 vinyl Electrical tape was introduced in the mid 40s. This advanced material provided dramatic advantages over friction tape , including improved adhesion and moisture protection. vinyl tapes have been refi ned substantially over the years, and other tape products have been added as well. Today s tapes offer long-term performance, excellent adhesion, and temperature resistance not to mention smooth unwind from the roll. Resistance to adhesive transfer, superior conformability, high tensile strength, good elastic memory and recovery, and wider installation and operational temperature ranges characterize premium vinyl Electrical bar. A common method of in-sulating a bus bar connection is to fi rst wrap it with two layers of varnished cambric. The subsequent steps consist of fou r ha l f-l appe d l ayers of r ubber or r ub -ber mastic followed by two half-lapped layers of premium vinyl tape .

9 Electrical tapes are versatile, suited to a multitude of tasks, and when installed properly provide a long-term, effective insulation. According to Anderson, both the NJATC headquarters and local training efforts are strongly supported by industry suppliers, which provide sample products and assist with course development and hands-on instruction. In addition, manufacturers of electri-cal-grade tapes are generally willing to provide technical support and instruc-tion on proper Taping techniques. There are many kits and products available to electricians today that simplify their work and help increase productivity, Anderson says. The properties of Electrical tapes have also been steadily improved over the years. These proven products can be adapted to many important Electrical insulation tasks, and they continue to be valuable assets for our industry.

10 For that reason, we continue to stress the importance of Taping skills and strong product and application knowledge. Goodman is a technical service engineer and Brown is a technical service senior engineer with 3M in Austin, UsesVinylTa p e sRubber Ta p e sVarnishedCambricMastic & Filler Putty TapesProtective jacketingXXElectrical insulationXXXXM oisture sealingXXID and color-codingXHarness and bundlingXMechanical paddingXXXS hapingXXXRe-entryXXThe primary uses for each of the different types of tapes available are outlined in the table with permission from the January 2006 issue of Electrical Construction & Maintenance. ( )Copyright 2006, Prism Business Media. All rights